Downhole tubular length compensating system and method

ABSTRACT

Disclosed herein is a downhole tubular length compensating system. The system includes, a tubular having a plurality of length adjustable sections, and spacings between adjacent length adjustable sections are set to overcome frictional forces anticipated along the tubular.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/052,919, filed on May 13, 2008, the entire contents of which are incorporated herein by reference. This application is a continuation-in-part of U.S. patent application Ser. No. 12/136,377, filed on Jun. 10, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND

In horizontal and highly deviated wells friction between a tubular and the walls of the well can be quite large due to factors, such as, the weight of the tubular, and fluid contained therein, and collapse of the formation against the tubular, for example. The longer a length of tubular encountering such conditions the greater the frictional forces become. In fact, frictional forces over a length of tubular can be high enough to result in damage to the tubular in response to forces urging the tubular to move longitudinally. Motive forces of such magnitude can be generated by longitudinal expansion and contraction of the tubular as temperatures of the tubular change. Systems to allow nondestructive longitudinal movement of tubulars under such conditions would be well received by the industry.

BRIEF DESCRIPTION

Disclosed herein is a downhole tubular length compensating system. The system includes, a tubular having a plurality of length adjustable sections, and spacings between adjacent length adjustable sections are set to overcome frictional forces anticipated along the tubular.

Further disclosed herein is a method of locally relieving longitudinal stress in a downhole tubular. The method includes, length adjusting a plurality of length adjustable sections of a downhole tubular in response to expansion and contraction of the downhole tubular between adjacent length adjustable sections.

Further disclosed herein is a downhole tubular length change compensating system. The system includes, a tubular having at least one length adjustable section between adjacent joints, and adjustability of the length adjustable sections is set to accommodate expansion and contraction of the tubular between adjacent length adjustable sections.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 depicts a quarter cross sectional view of a tubular length compensating system disclosed herein;

FIG. 2 depicts a quarter cross sectional view of an alternate tubular length compensating system disclosed herein shown without an adjustment to the length thereof;

FIG. 3 depicts a quarter cross sectional view of the tubular length compensating system of FIG. 2 shown with a length adjustment to a length thereof; and

FIG. 4 depicts a quarter cross sectional view of an alternate embodiment of a tubular length compensating system.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1, an embodiment of the tubular length compensating system 10 is illustrated. The compensating system 10 includes, a tubular 14 having a plurality of length adjustable sections 18 (one being shown). One length adjustable section 18 illustrated in this embodiment includes a deformable portion 22 illustrated here as a convoluted portion, made of metal, having a series of alternating sections with reduced perimeters 26 and expanded perimeters 30. The deformable portion 22 can alternately consist of deformable formations such as those disclosed in U.S. Pat. No. 6,896,049 to Moyes, for example, the contents of which are incorporated by reference herein in their entirety. The convoluted portion 22 can be longitudinally compressible, longitudinally expandable, or both in response to loads applied thereto. The loads needed to compress or expand the convoluted portion 22 being less than the loads needed to compress, expand or damage other portions of the tubular 14. The ability of the convoluted portion 22 to longitudinally compress and expand provides length adjustability to the tubular 14. The design of the convoluted portion 22, in this embodiment, allows for such compression and expansion to take place within elastic limits of the material from which the convoluted portion 22 is fabricated, with metal being disclosed herein as the material of choice for the convoluted portion 22 while alternate materials such as polymers and elastomers are contemplated as also being usable. By maintaining deformation of the convoluted portion 22 within the elastic limits of the material the deformation and thus the compression and expansion are reversible an indefinite number of cycles.

In addition to the reversibility of the length adjustability, the convoluted portion 22 also allows compression and expansion to take place while maintaining a fluidic seal between the inside and the outside of the tubular 14. This seal is maintained without a sliding seal which may be beneficial since sliding seal integrity can be questionable downhole due to high temperatures, high pressures, contamination and caustic fluids typically encountered in downhole environments.

An amount of length adjustability provided by the convoluted portion 22 can be controlled in different ways with one such way being disclosed in this embodiment. A pipe 34 is fixedly attached to a first portion 38 of the tubular 14 by a weld 42 while alternate methods of attachment, such as, by threadable engagement, for example, may be employed. A second portion 46 of the tubular 14, on an opposing side of the length adjustable section 18 than the first portion 38, is slidably engaged with the pipe 34. A pair of standoffs 50, 54 protruding radially inwardly from the pipe 34 straddle a standoff 58 protruding radially outwardly from the second portion 46. The relative positioning of the standoffs 50, 54, 58 define the range of compression and expansion that the length adjustable section 18 is allowed to undergo. During compression and expansion the second portion 46 moves relative to the pipe 34 thereby causing the standoff 58 to move in relation to the standoffs 50, 54. Under compression the standoff 58 moves toward the standoff 50 until contact is made therebetween, limiting the compressive length of adjustment. Similarly, under expansion the standoff 58 moves toward the standoff 54 until contact is made therebetween, limiting the expansive length of adjustment. With the foregoing, a tool designer can set a total amount of travel allowed by a length adjustable section 18 through the spacing of the standoffs 50 and 54. To control how much of the total travel is compressive versus expansive the designer sets an initial position of the standoff 58 relative to the standoffs 50, 54.

A release member 62, ring engaged between the second portion 46 and the pipe 34, sets the initial position of the standoff 58 relative to the standoffs 50 and 54, in this embodiment. The release member 62 locks the second portion 46 in a position relative to the pipe 34 until a threshold load is achieved at which the release member 62 fails thereby allowing the load to be applied to the length adjustable section 18 directly. The release member 62 prevents inadvertent length adjustments from occurring, such as during running of the tubular into or out of a wellbore, for example.

As discussed above, high frictional forces between the tubular 14 and walls 66 of a wellbore 70 can make moving the tubular 14 within the wellbore 70 very difficult. This condition is exacerbated in horizontal or highly deviated wells. The longer the section of the tubular 14 within the wellbore 70 the greater the frictional forces therebetween. Embodiments disclosed herein position a plurality of the length adjustable sections 18 along the tubular 14 to prevent a build up of potentially damaging longitudinally compressive or longitudinally tensive forces due to expansion or contraction of the tubular 14 due to temperature changes therein. Embodiments can include at least one length adjustable section 18 between any two joints of tubing. Spacing between adjacent length adjustable sections 18 can be established based upon anticipated frictional forces along the tubular 14. For example, a designer can determine longitudinal loads (both compressive and expansive) that if applied to the tubular 14 would cause damage thereto. The designer can also estimate a length of the tubular 14 under specific, anticipated, downhole conditions that may generate these destructive longitudinal loads based on parameters of the tubular 14 including, for example, material and coefficient of thermal expansion. With such information, the designer can space adjacent length adjustable sections 18 at distances apart so that the tubular 14 is able to overcome the frictional force (and the forces needed release the release member 62 and to adjust a length of the length adjustable sections 18), and thereby slide relative to the walls 66, without resulting in damage to the tubular 14. Additionally, the designer can set an adjustable length of the length adjustable sections 18 to assure that the anticipated change in length of the tubulars 14 (due to thermal expansion and contraction of the tubular, for example), between adjacent length adjustable sections 18, can be fully accommodated thereby. In summary, by positioning a plurality of the length adjustable sections 18 along a length of the tubular 14, embodiments disclosed herein permit localized compressive and tensive loads in the tubular 14 to be relieved locally by a shortening or lengthening of a plurality of the length adjustable sections 18 of the tubular 14.

Referring to FIGS. 2 and 3, an alternate embodiment of a length compensating system 110 disclosed herein is illustrated. A primary difference between the two systems 10 and 110 is that the length adjustable section 18 of system 10 has been replaced with a length adjustable section 118 in system 110. The length adjustable section 118 includes a release joint 116, such as, a shear joint, for example, having a shear plane 120. The shear plane 120 is shearable at a selected level of compressive or tensive load. Upon shearing of the shear plane 120 a first part 124 of the shear joint 116 is movable relative to a second part 128 of the shear joint 116. During compressive movement the parts 124 and 128 overlap, similar to a lap joint arrangement, and may form a seal therebetween. During expansive movement the parts 124 and 128 move away from one another. An optional seal 132, shown herein as an o-ring, may form a slidable seal between the second portion 46 and the pipe 34 to maintain a seal across the system 110 during longitudinal adjustment thereof.

Referring to FIG. 4, an embodiment of an alternate length compensating system 210 disclosed herein is illustrated. The system 210 includes, a coupler 214 having a length adjustable section 218 positioned between two tubulars 222, 226. The length adjustable section 218 has a deformable portion 222 constructed herein as a reduced wall section. Axial loads applied to the deformable portion 222, from the tubulars 224, 226, can cause the deformable portion 222 to plastically deform by buckling, in the case of compressive loading, and through elongation or rupture, in the case of tensive loading. A sleeve 230 and a lock nut 234 are engaged with the two tubulars 224, 226 to provide structural stability across the length adjustable section 218 during length adjustment when the strength of the coupler 214 is compromised upon plastic deformation thereof. At least one of the sleeve 230 and lock nut 234 are slidably engaged with at least one of the tubulars 224, 226 to permit the length adjustment thereacross without appreciably adding to a load required to cause the readjustment in length.

The slidable engagement between the sleeve 230, or the lock nut 234, and the tubulars 224, 226, may be packed with steel fiber 238, or wire mesh, in a case where leakage therebetween is allowed as long as it is filtered such as in a sand screen application, as illustrated in herein. For applications requiring a fluidic seal, o-rings (not shown), or other slidably sealing members may be employed between the sleeve 230 or lock nut 234 and the tubulars 224, 226.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

1. A downhole tubular length compensating system, comprising a tubular having a plurality of length adjustable sections, and spacings between adjacent length adjustable sections being set to overcome frictional forces anticipated along the tubular.
 2. The downhole tubular length compensating system of claim 1, wherein the plurality of length adjustable sections is adjustable in response to longitudinal forces applied thereto.
 3. The downhole tubular length compensating system of claim 2, wherein the plurality of length adjustable sections are adjusted by shortening thereof.
 4. The downhole tubular length compensating system of claim 1, further comprising a force failing member in operable communication with the plurality of length adjustable sections.
 5. The downhole tubular length compensating system of claim 4, wherein the force failing member is one of a shear joint and a lock ring.
 6. The downhole tubular length compensating system of claim 1, further comprising: a first portion of the tubular being on a first side of each length adjustable portion; and a second portion of the tubular on a second side of each length adjustable portion being movable relative to each length adjustable portion.
 7. The downhole tubular length compensating system of claim 6, wherein the first portion is fixedly attached to a pipe and the second portion is slidably engaged with the pipe.
 8. The downhole tubular length compensating system of claim 7, wherein the first portion is fixedly attached to the pipe by one of threadable engagement and welding.
 9. The downhole tubular length compensating system of claim 7, further comprising a seal slidably engaged between the second portion and the pipe.
 10. The downhole tubular length compensating system of claim 1, wherein at least one of the plurality of length adjustable sections include a deformable member.
 11. The downhole tubular length compensating system of claim 10, wherein the deformable member is metal.
 12. The downhole tubular length compensating system of claim 10, wherein deformation of the deformable member is reversible.
 13. The downhole tubular length compensating system of claim 1, wherein the plurality of length adjustable sections are configured to maintain a seal across a wall of the tubular during length adjustments without a sliding seal.
 14. The downhole tubular length compensating system of claim 1, wherein a length adjustability of the plurality of length adjustable sections is reversible.
 15. The downhole tubular length compensating system of claim 1, wherein a length adjustability of the plurality of length adjustable sections is in response to expansion and contraction of the tubular due to temperature changes therein.
 16. The downhole tubular length compensating system of claim 1, wherein a length adjustability of the plurality of length adjustable sections is selected based on parameters of the tubular between the adjacent length adjustable sections.
 17. The downhole tubular length compensating system of claim 16, wherein the parameters include at least one of material and coefficient of thermal expansion of the tubular.
 18. The downhole tubular length compensating system of claim 16, wherein the wherein adjustment of each of the plurality of length adjustable sections includes plastic deformation thereof.
 19. A method of locally relieving longitudinal stress in a downhole tubular, comprising length adjusting a plurality of length adjustable sections of a downhole tubular in response to expansion and contraction of the downhole tubular between adjacent length adjustable sections.
 20. A downhole tubular length change compensating system, comprising a tubular having at least one length adjustable section between adjacent joints, adjustability of the length adjustable sections being set to accommodate expansion and contraction of the tubular between adjacent length adjustable sections. 